As a winter storm approaches, timing the activation and deactivation of winter maintenance operations has a significant impact on safety and budgeting. This synthesis report focuses on state practices in winter maintenance fleet activation for winter storms. A literature review and a survey of 25 Clear Roads states indicates that most agencies summon half or more of their workforce to come in before a storm arrives, if only just before. Meteorologists have become increasingly involved in winter maintenance programming, and a broad range of sophisticated systems, weather data and forecast sources are drawn upon in activation
decisions, which are usually made at the district or regional level.
Activation and deactivation procedures are data-heavy activities. Fleet activation practices seem equally informed by current and forecast data. Many states have specific thresholds (fixed numbers) for air temperature, pavement temperature, precipitation levels and other factors that trigger activation.
Decisions about when to deactivate forces (send crews home) tend to be driven by a combination of fixed value thresholds and field observations. Current conditions are given more weight than forecasts, with the significant exception of precipitation forecasts. The increasing role of meteorology in winter maintenance activities suggests they may be becoming more data-driven.
Anti-icing (also known as “pre-treating”) is the winter road maintenance practice of applying a liquid or solid material intended to depress the freezing point of water in order to prevent winter storm precipitate from bonding to roadway pavement. Anti-icing may be performed hours (or even days) before a winter storm event begins; it can also be performed after ice or snow begins to fall in order to keep pavements as clear of ice and snow as possible. Salt [sodium chloride] brine and other chloride
liquids are widely used for anti-icing. Historically, materials other than liquids, such as dry and prewetted salt/solids, have also been used by winter maintenance agencies for anti-icing.
This Clear Roads synthesis project sought to learn how and the extent to which agencies use prewetted salts/solids for anti-icing, the conditions under which they are used, their effectiveness, cost-effectiveness and agencies’ response to environmental concerns about anti-icing salt use. The investigation included a national survey of state department of transportation winter maintenance experts that gathered information about materials used for anti-icing, including reasons why materials were selected, how they were prepared and applied, and their effectiveness, with particular focus on the use of prewetted solids. The results of a literature search supplemented the survey findings.
Accurate calibration of material application equipment is the primary means through which a transportation agency can avoid overapplication of salt and other winter maintenance materials to counter snow and ice on roadways. Methods of effective calibration for salt spreaders have been examined extensively and presented in many published reports and manuals. Manufacturers include comprehensive guides with their equipment. Thus, instruction and guidance is widely available. Clear Roads member agencies were interested in learning more about calibration accuracy of equipment over time: the practices and experiences of agencies that could help identify factors that may diminish calibration accuracy of equipment over weeks and months of use in extreme conditions.
Through a literature search and a survey of Clear Roads member departments of transportation (DOTs) and others, this synthesis gathered information about the types of material application equipment that agencies use, schedules and methods of calibration, training protocols, respondents’ perceptions of the accuracy of equipment, and types and qualities of materials.
This research brief was produced as part of Clear Roads project CR17-02, "Standard Specifications for Plow Blades with Carbide Inserts," published April 2020.
This research brief was created as part of Clear Roads project CR17-01 "Integrating Advanced Technologies into Winter Operations Decisions," published December 2020
Maximizing the conspicuity of state department of transportation (DOT) fleet vehicles and equipment used for summer and winter maintenance is expected to improve highway safety and increase mobility for both the motoring public and the vehicle or equipment operator.
This synthesis sought to build on the October 2015 Clear Roads report Use of Equipment Lighting During Snowplow Operations. A review of domestic and international research and other relevant resources gathered information about the lighting, paint colors and retroreflective taping patterns used to enhance the conspicuity of state DOT maintenance vehicles and equipment. The literature search also sought information about the practices used to enhance the conspicuity of vehicles used at airports, for emergency purposes and by law enforcement, and investigated how lighting, color and retroreflective markings can improve general vehicle conspicuity. The report concludes with a brief examination of the use of high-visibility garments to improve pedestrian and worker safety.
